Hybrid powertrain

ABSTRACT

A transmission includes a first planetary gearset and a second planetary gearset, each having a respective first planetary member, a respective second planetary member, and a respective third planetary member. The planetary members of the first planetary gearset are coaxially disposed on, and selectively rotatable about, a first axis. The planetary members of the second planetary gearset are coaxially disposed on, and selectively rotatable about, a second axis. An axis transfer mechanism including meshing gears transmits torque between the first and second planetary gearsets.

TECHNICAL FIELD

This invention relates to hybrid vehicle powertrains.

BACKGROUND

Electrically variable vehicle transmissions (EVTs) typically employ twoelectric motor/generators. The electric motor/generators are coaxiallyoriented with an input shaft connectable to an engine, an output shaft,and a plurality of planetary gearsets each having respective first,second, and third members. Each motor/generator is operatively connectedto a respective member of one of the planetary gearsets to provide arange or mode of transmission operation characterized by a continuouslyvariable speed ratio between the input shaft and the output shaft. Thecontinuously variable speed ratio is proportional to the speed of one ofthe motor/generators. The motor/generators are operatively connected toan energy storage device, such as a battery, to transmit energy theretowhen operating as a generator, and to receive energy therefrom whenacting as a motor.

SUMMARY

According to a first aspect of the disclosure, a transmission includesan input member, an output member, a first motor/generator having afirst rotor, a second motor/generator having a second rotor, a firstplanetary gearset, a second planetary gearset, and a third planetarygearset each having a respective first planetary member, a respectivesecond planetary member, and a respective third planetary member.

The first, second, and third planetary members of the first planetarygearset and the first rotor are coaxially disposed on, and selectivelyrotatable about, a first axis. The first, second, and third planetarymembers of the second planetary gearset and the first, second, and thirdplanetary members of the third planetary gearset are coaxially disposedon, and selectively rotatable about, a second axis. The second rotor isdisposed on, and selectively rotatable about, a third axis. The outputmember is disposed on, and selectively rotatably about, a fourth axis.

The transmission further includes a first axis transfer mechanismoperatively interconnecting the second planetary gearset and the firstplanetary gearset and is configured to transmit torque therebetween. Asecond axis transfer mechanism operatively interconnects the secondrotor and the third planetary gearset and is configured to transmittorque therebetween. A third axis transfer mechanism operativelyinterconnects the first planetary gearset, the third planetary gearset,and the output member and is configured to transmit torque therebetween.

The transmission packages in tight cross car vehicle applications whileminimizing parasitic losses, thereby increasing overall efficiency.

According to a second aspect of the disclosure, a transmission includesan input member, an output member, a stationary member, and a firstplanetary gearset and a second planetary each having a respective firstplanetary member, a respective second planetary member, and a respectivethird planetary member. The planetary members of the first planetarygearset are coaxially disposed on, and selectively rotatable about, afirst axis. The planetary members of the second planetary gearset arecoaxially disposed on, and selectively rotatable about, a second axis.

The transmission also includes a first motor/generator having a firstrotor operatively connected to the third planetary member of the firstplanetary gearset for unitary rotation therewith. A secondmotor/generator has a second rotor that is operatively connected to thethird planetary member of the second planetary gearset for unitaryrotation therewith. A first axis transfer mechanism has a first axistransfer gear member, a second axis transfer gear member meshinglyengaged with the first axis transfer gear member, and a third axistransfer gear member meshingly engaged with the second axis transfergear member.

A second axis transfer mechanism is operatively connected to the firstaxis transfer gear member and the output member, and is configured totransmit torque from the first axis transfer gear member to the outputmember.

The above features and advantages and other features and advantages ofthe present invention are readily apparent from the following detaileddescription of the best modes for carrying out the invention when takenin connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic lever diagram depicting a first transmission inaccordance with the claimed invention;

FIG. 2 is a schematic, sectional, side view of the transmission of FIG.1 taken about a first plane;

FIG. 3 is a schematic, sectional, side view of the transmission of FIGS.1 and 2 taken about a second plane;

FIG. 4 is a schematic, sectional, side view of a portion of thetransmission of FIGS. 1-3; and

FIG. 5 is a schematic lever diagram depicting a second transmission inaccordance with the claimed invention.

DETAILED DESCRIPTION

Referring to FIG. 1, a vehicle powertrain 10 is schematically depicted.The powertrain 10 includes an engine 12 and a transmission 14. Thetransmission 14 includes an input member 16 and an output member 18. Theinput member 16 is operatively connected to the crankshaft of the engine12 through a powertrain damper/isolator (not shown) to receive torquetherefrom. The output member 18 is operatively connected to thevehicle's drive wheels 22 to transmit torque thereto via a differentialassembly (not shown). The transmission 14 also includes first, secondand third planetary gearsets 24, 26, 28.

Referring to FIGS. 1 and 2, each of the planetary gearsets 24, 26, 28includes respective first, second, and third planetary members. In thefirst planetary gearset 24, the first planetary member is a ring gearmember 30, the second planetary member is a sun gear member 32, and thethird planetary member is a planet carrier member 34. The firstplanetary gearset includes at least one pinion gear 36 that is rotatablyconnected to the planet carrier member 34, and that is meshingly engagedwith both the ring gear member 30 and the sun gear member 32.

In the second planetary gearset 26, the first planetary member is a ringgear member 38, the second planetary member is a sun gear member 40, andthe third planetary member is a planet carrier member 42. The secondplanetary gearset includes at least one pinion gear 44 that is rotatablyconnected to the planet carrier member 42, and that is meshingly engagedwith both the ring gear member 38 and the sun gear member 40.

In the third planetary gearset 28, the first planetary member is a ringgear member 46, the second planetary member is a sun gear member 48, andthe third planetary member is a planet carrier member 50. The secondplanetary gearset includes at least one pinion gear 52 that is rotatablyconnected to the planet carrier member 50, and that is meshingly engagedwith both the ring gear member 46 and the sun gear member 48. It shouldbe noted that, where used in the claims, first, second, and thirdmembers of planetary gearsets do not necessarily refer to a member of aparticular type; thus, for example, a first member may be any one of aring gear member, sun gear member, or planet carrier assembly.Similarly, as used in the claims, the respective first, second, or thirdmembers of two or more gearsets may or may not be the same type ofmember.

The input member 16 is operatively connected to sun gear member 32 forunitary rotation therewith. Accordingly, the sun gear member 32 isoperatively connected to the input member 16 to receive torquetherefrom. A first motor/generator 58 includes a stator 60 and a firstrotor 62. The stator 60 is connected to a stationary member, such as thetransmission housing 98. The ring gear 30 is operatively connected tothe first rotor 62 to receive torque therefrom. More specifically, inthe embodiment of FIG. 1, ring gear 30 is operatively connected to thefirst rotor 62 for unitary rotation therewith.

A first axis transfer mechanism, which, in the embodiment depicted, is afirst chain drive 64, operatively interconnects the second planetarygearset 26 and the first planetary gearset 24 and is configured totransmit torque therebetween. More specifically, the ring gear member 30of the first planetary gearset 24 is operatively connected to the planetcarrier member 42 of the second planetary gearset 26 via the first chaindrive 64 such that the first chain drive 64 transmits torque between thering gear member 30 and the planet carrier member 42.

The first chain drive 64 includes a first sprocket 66 operativelyconnected to ring gear member 30, and, correspondingly, to the firstrotor 62, for unitary rotation therewith. The first chain drive 64 alsoincludes a second sprocket 68 operatively connected to planet carriermember 42 for unitary rotation therewith. A first roller chain 70engages both the first and second sprockets 66, 68 to transfer motiontherebetween.

A second motor/generator 72 includes a stator 74 and a second rotor 76.A second axis transfer mechanism, which is a second chain drive 78 inthe embodiment depicted, operatively interconnects the second rotor 76and the third planetary gearset 28 and is configured to transmit torquetherebetween. More specifically, in the embodiment depicted, the sungear member 48 of the third planetary gearset 28 is operativelyconnected to the second rotor 76 to receive torque therefrom via thesecond axis transfer mechanism.

The second chain drive 78 includes a third sprocket 80 operativelyconnected to sun gear member 48 for unitary rotation therewith. Thechain drive 78 also includes a fourth sprocket 82 operatively connectedto rotor 76 for unitary rotation therewith. A second roller chain 84interconnects and engages both the third and fourth sprockets 80, 82 totransfer motion therebetween. The stator 74 is connected to a stationarymember, such as the transmission housing 98.

A third axis transfer mechanism 86 operatively interconnects the firstplanetary gearset 24, the third planetary gearset 28, and the outputmember 18 and is configured to transmit torque therebetween. In theembodiment depicted, the third axis transfer mechanism 86 has a firstaxis transfer gear member 88, a second axis transfer gear member 90, athird axis transfer gear member 92, and a fourth axis transfer gear 94.

The first axis transfer gear member 88 and the second axis transfer gearmember 90 are operatively connected to the planet carrier member 50 ofthe third planetary gearset 28 for unitary rotation therewith (and thusgear member 88 and gear member 90 are rigidly interconnected for unitaryrotation with each other). The third axis transfer gear member 92 ismeshingly engaged with the second axis transfer gear member 90 and isoperatively connected to the planet carrier member 34 of the firstplanetary gearset 24 for unitary rotation therewith. The fourth axistransfer gear member 94 is meshingly engaged with the first axistransfer gear member 88 and is operatively connected to the outputmember 18 for unitary rotation therewith.

Thus, planet carrier member 50 is operatively connected to the outputmember 18 to transmit torque thereto via the axis transfer mechanism 86.Planet carrier 34 is also operatively connected to the output member 18to transmit torque thereto via the axis transfer mechanism 86. Torquemay be transmitted from planet carrier member 34 to the output member 18via gear members 92, 90, 88, and 94. Torque may also be transmitted fromplanet carrier member 50 to the output member 18 via gear members 88 and94.

Referring to FIGS. 1 and 3, the transmission 14 includes a first torquetransmitting mechanism, namely, a first brake 96, which is operativelyconnected to the ring gear member 38 of the second planetary gearset 26and the stationary member 98. The first brake 96 is selectivelyengageable to couple the ring gear member 38 of the second planetarygearset 26 to the stationary member 98; that is, the first brake 96 isconfigured to selectively couple ring gear member 38 to the stationarymember 98 to prevent the rotation of the ring gear member 38 relative tothe housing 98.

The first brake 96 is positioned about a different axis of rotation fromring gear member 38. A fourth axis transfer mechanism 100 has a fifthaxis transfer gear member 102 operatively connected to the ring gearmember 38 of the second planetary gearset 26 for unitary rotationtherewith, and a sixth axis transfer gear member 104 meshingly engagedwith the fifth axis transfer gear member 102 and operatively connectedto the first brake 96.

When the brake 96 is engaged, the brake 96 couples gear member 104 tothe housing 98, thereby preventing the rotation of the gear member 104relative to the housing 98. When gear member 104 is coupled to thehousing 98, rotation of gear member 102 and ring gear member 38 is alsoprevented. When the brake 96 is disengaged, the gear member 104 canrotate freely with respect to the housing 98, and thus ring gear member38 and gear member 102 can also rotate freely when the brake 96 isdisengaged.

Ring gear member 46 of the third planetary gearset 28 is operativelyconnected to the sun gear member 40 of the second planetary gearset 26for unitary rotation together. The transmission 14 includes a secondtorque transmitting mechanism, namely, a second brake 106, which isconfigured to selectively couple ring gear member 46 and the sun gearmember 40 to the transmission housing 98 to prevent the rotation of thering gear member 46 and the sun gear member 40.

The second brake 106 is positioned about a different axis of rotationfrom ring gear member 46 and sun gear member 40. A fifth axis transfermechanism 108 has a seventh axis transfer gear member 110 operativelyconnected to the ring gear member 46 of the third planetary gearset 28for unitary rotation therewith, and an eighth axis transfer gear member112 meshingly engaged with the seventh axis transfer gear member 110.The eighth axis transfer gear member 112 is operatively connected to thesecond brake 106.

When the brake 106 is engaged, the brake 106 couples gear member 112 tothe housing 98, thereby preventing the rotation of the gear member 112relative to the housing 98. When gear member 112 is coupled to thehousing 98, rotation of gear member 110, ring gear member 46, and sungear member 40 is also prevented. When the brake 106 is disengaged, thegear member 112 can rotate freely with respect to the housing 98, andthus ring gear member 46, sun gear member 40, and gear member 110 canalso rotate freely when the brake 106 is disengaged.

Referring specifically to FIGS. 2 and 3, the input member 16; the first,second, and third planetary members of the first planetary gearset 24(i.e., ring gear member 30, planet carrier member 34, and sun gearmember 32); gear member 92; rotor 62; and sprocket 66 are coaxiallydisposed, and selectively rotatable, about a first axis 116. The first,second, and third members of the second planetary gearset 26 (i.e., ringgear member 38, sun gear member 40, planet carrier member 42); thefirst, second, and third members of the third planetary gearset 28(i.e., ring gear member 46, sun gear member 48, planet carrier member50); gear members 88, 90, 102, 110, and sprockets 68, 80 are coaxiallydisposed, and selectively rotatable, about a second axis 120. The secondrotor 76 and sprocket 82 are coaxially disposed, and selectivelyrotatable, about a third axis 124. Output member 18 and gear member 94are coaxially disposed, and selectively rotatable, about a fourth axis132. Gear members 104, 112 and brakes 96, 106 are coaxially disposed,and selectively rotatable, about a fifth axis 128.

Referring to FIG. 4, a first portion 136 of the planet carrier member 34of the first planetary gearset 24 is disposed on a first side 138 of thering gear member 30. The pinion gears 36 are connected to shafts 140;shafts 140 are connected to the first portion 136 of the planet carriermember 34. A second portion 142 of the planet carrier member 34 extendsaxially from the first side 138 of the ring gear member 30 to a secondside 146 of the ring gear member 30. The second portion 142 is disposedradially outward relative to the ring gear member 30. The second portion142 is operatively connected to the third axis transfer gear member 92,which is disposed on the second side 146 of the ring gear member 30.

The third axis transfer gear member 92 rotates about grounded structure148, i.e., structure that is part of, or rigidly connected to, thehousing 98. A tapered bearing 150 is disposed between the structure 148and gear member 92 to axially retain the planet carrier member 34 andthe gear member 92.

The transmission 14 provides compact, flat vehicle packaging. Efficiencyadvantages may be provided by geared low loss band clutches, i.e.,brakes 96, 106 (no high pressure/high flow pump). Chain drives 64, 78provide low loss axis transfers. The speed of the second motor/generator72 may be reduced using off-axis ratio (30% torque/size reduction). Thearchitecture of the transmission 14 is motor length flexible, whichenables the use of induction motors.

Referring to FIG. 5, another powertrain 210 in accordance with theclaimed invention is schematically depicted. The powertrain 210 includesan engine 212 and a transmission 214. The transmission 214 includes aninput member 216 and an output member 218. The input member 216 isoperatively connected to the crankshaft of the engine 212 through apowertrain damper/isolator (not shown) to receive torque therefrom. Theoutput member 218 is operatively connected to the vehicle's drive wheels222 to transmit torque thereto via a differential assembly (not shown).The transmission 214 also includes first and second planetary gearsets224, 226.

Each of the planetary gearsets 224, 226 includes respective first,second, and third planetary members. In the first planetary gearset 224,the first planetary member is a ring gear member 230, the secondplanetary member is a sun gear member 232, and the third planetarymember is a planet carrier member 234. The first planetary gearsetincludes at least one pinion gear (such as the one shown at 36 in FIGS.2 and 4) that is rotatably connected to the planet carrier member 234,and that is meshingly engaged with both the ring gear member 230 and thesun gear member 232.

In the second planetary gearset 226, the first planetary member is aring gear member 238, the second planetary member is a sun gear member240, and the third planetary member is a planet carrier member 242. Thesecond planetary gearset 226 includes at least one pinion gear (such asthe one shown at 44 in FIG. 2) that is rotatably connected to the planetcarrier member 242, and that is meshingly engaged with both the ringgear member 238 and the sun gear member 240.

A first motor/generator 243 includes a stator 244 and a first rotor 245.The stator 244 is connected to a stationary member, such as thetransmission housing 298. A second motor/generator 246 includes a stator247 and a second rotor 248. The stator 247 is connected to a stationarymember, such as the transmission housing 298.

The sun gear member 232 is operatively connected to the first rotor 245for unitary rotation therewith. The planet carrier member 234 isoperatively connected to the input member 216 for unitary rotationtherewith. Sun gear member 240 is operatively connected to the secondrotor 248 for unitary rotation therewith. Ring gear member 238 isoperatively connected to the housing 298 such that the ring gear member238 is stationary.

The transmission 214 includes at least one axis transfer mechanism thatoperatively interconnects one of the planetary members of the firstplanetary gearset 224, one of the members of the second planetarygearset 226, and the output member 218. The at least one axis transfermechanism is configured such that torque is transmissible from the firstplanetary gearset 224 and from the second planetary gearset 226 to theoutput member 218 through the at least one axis transfer mechanism. Inthe embodiment depicted, two axis transfer mechanisms 249, 250 cooperateto interconnect the first planetary gearset 224, the second planetarygearset 226, and the output member 218 such that torque is transmissibletherebetween.

More specifically, a first axis transfer mechanism 249 includes a firstaxis transfer gear member 252, a second axis transfer gear member 256meshingly engaged with the first axis transfer gear member 252, and athird axis transfer gear member 260 meshingly engaged with the secondaxis transfer gear member 256. Thus, the second axis transfer gearmember 256 acts as an idler gear. A second axis transfer mechanism 250includes a fourth axis transfer gear member 264 operatively connected tothe first axis transfer gear member 252 for unitary rotation therewith,a fifth axis transfer gear member 268 meshingly engaged with the fourthaxis transfer gear member 264, a sixth axis transfer gear member 272operatively connected to the fifth axis transfer gear member 268 forunitary rotation therewith, and a seventh axis transfer gear member 276meshingly engaged with the sixth axis transfer gear member 272 andoperatively connected to the output member 218 for unitary rotationtherewith. The first and fourth axis transfer gear members 252, 264 areoperatively interconnected for unitary rotation.

The first, second, and third planetary members 230, 232, 234 of thefirst planetary gearset 224, the input member 216, the first rotor 245,the first axis transfer gear member 252, and the fourth axis transfergear member 264 are coaxially disposed on, and selectively rotatableabout, a first axis 280. The first, second, and third members 238, 240,242 of the second planetary gearset 226, the second rotor 248, and thethird axis transfer gear member 260 are coaxially disposed on, andselectively rotatable about, a second axis 284. The output member 218 iscoaxially disposed on, and selectively rotatable about, a third axis292. The fifth and sixth axis transfer gear members 268, 272 arecoaxially disposed on, and selectively rotatable about, a fourth axis288.

Ring gear member 230 is operatively connected to the first axis transfergear 252 for unitary rotation therewith. Ring gear member 230 is alsooperatively connected to the fourth axis transfer gear member 264 forunitary rotation therewith, since the first and fourth axis transfergears 252, 264 are interconnected for unitary rotation. Planet carriermember 242 is operatively connected to the third axis transfer gearmember 260 for unitary rotation.

The transmission 214 of FIG. 5 is a reduced content, off-axis, two modeelectrically variable transmission. The transmission 214 ischaracterized by on-axis input split with mechanical point at anoverdrive ratio, and an additional planetary gearset to reduce thetorque requirements of the second motor/generator 246. The axis transfermechanism 249 reduces on-axis transmission length and providesadditional motor/generator 246 ratio.

While the best modes for carrying out the invention have been describedin detail, those familiar with the art to which this invention relateswill recognize various alternative designs and embodiments forpracticing the invention within the scope of the appended claims.

The invention claimed is:
 1. A transmission comprising: an input member;an output member; a first motor/generator having a first rotor; a secondmotor/generator having a second rotor; a first planetary gearset, asecond planetary gearset, and a third planetary gearset each having arespective first planetary member, a respective second planetary member,and a respective third planetary member; said first, second, and thirdplanetary members of the first planetary gearset, said input member, andsaid first rotor being coaxially disposed on, and selectively rotatableabout, a first axis; said first, second, and third planetary members ofthe second planetary gearset and said first, second, and third planetarymembers of the third planetary gearset being coaxially disposed on, andselectively rotatable about, a second axis; said second rotor beingdisposed on, and selectively rotatable about, a third axis; said outputmember being disposed on, and selectively rotatably about, a fourthaxis; a first axis transfer mechanism operatively interconnecting thesecond planetary gearset and the first planetary gearset and configuredto transmit torque therebetween; a second axis transfer mechanismoperatively interconnecting the second rotor and the third planetarygearset and configured to transmit torque therebetween; and a third axistransfer mechanism operatively interconnecting the first planetarygearset, the third planetary gearset, and the output member andconfigured to transmit torque therebetween.
 2. The transmission of claim1, wherein the first planetary member of the first planetary gearset isoperatively connected to the first axis transfer mechanism and to thefirst rotor for unitary rotation therewith; wherein the second planetarymember of the first planetary gearset is operatively connected to theinput member for unitary rotation therewith; wherein the third planetarymember of the first planetary gearset is operatively connected to thethird axis transfer mechanism; wherein the second planetary member ofthe second planetary gearset is operatively connected to the firstplanetary member of the third planetary gearset for unitary rotationtherewith; wherein the third planetary member of the second planetarygearset is operatively connected to the first axis transfer mechanism;wherein the second planetary member of the third planetary gearset isoperatively connected to the second axis transfer mechanism; and whereinthe third planetary member of the third planetary gearset is operativelyconnected to the third axis transfer mechanism.
 3. The transmission ofclaim 2, wherein the first axis transfer mechanism is a first chaindrive having a first sprocket operatively connected to the first memberof the first planetary gearset for unitary rotation therewith, a secondsprocket operatively connected to the third member of the secondplanetary gearset for unitary rotation therewith, and a first rollerchain operatively engaging and interconnecting the first and secondsprockets; and wherein the second axis transfer mechanism is a secondchain drive having a third sprocket operatively connected to the secondmember of the third planetary gearset for unitary rotation therewith, afourth sprocket operatively connected to the second rotor for unitaryrotation therewith, and a second roller chain operatively engaging andinterconnecting the third and fourth sprockets.
 4. The transmission ofclaim 3, wherein the third axis transfer mechanism includes first,second, third, and fourth axis transfer gear members; wherein the firstaxis transfer gear member is operatively connected to the thirdplanetary member of the third planetary gearset for unitary rotationtherewith; wherein the second axis transfer gear member is operativelyconnected to the first axis transfer gear member for unitary rotationtherewith; wherein the third axis transfer gear member is meshinglyengaged with the second axis transfer gear member and operativelyconnected to the third member of the first planetary gearset for unitaryrotation therewith; and wherein the fourth axis transfer gear member ismeshingly engaged with the first axis transfer gear member andoperatively connected to the output member for unitary rotationtherewith.
 5. The transmission of claim 4, further comprising astationary member; a first brake operatively connected to the firstmember of the second planetary gearset and the stationary member, andbeing selectively engageable to couple the first member of the secondplanetary gearset to the stationary member; and a second brakeoperatively connected to the first member of the third planetary gearsetand the stationary member, and being selectively engageable to couplethe first member of the third planetary gearset to the stationarymember.
 6. The transmission of claim 5, wherein the first brake and thesecond brake are coaxially disposed on a fifth axis.
 7. The transmissionof claim 6, further comprising a fourth axis transfer mechanism having afifth axis transfer gear member operatively connected to the firstmember of the second planetary gearset for unitary rotation therewith,and a sixth axis transfer gear member meshingly engaged with the fifthaxis transfer gear member and operatively connected to the first brake;and a fifth axis transfer mechanism having a seventh axis transfer gearmember operatively connected to the first member of the third planetarygearset for unitary rotation therewith, and an eighth axis transfer gearmember meshingly engaged with the seventh axis transfer gear member andoperatively connected to the second brake.
 8. The transmission of claim2, wherein the third planetary member of the first planetary gearset isa planet carrier member; wherein one of the first and second members ofthe first planetary gearset is a ring gear member; wherein a portion ofthe planet carrier member extends axially from one side of the ring gearmember to the other side of the ring gear member; and wherein theportion of the planet carrier member is disposed radially outwardly fromthe ring gear member.
 9. The transmission of claim 2, wherein the firstplanetary member of the first planetary gearset is a ring gear member;wherein the second planetary member of the first planetary gearset is asun gear member; wherein the third planetary member of the firstplanetary gearset is a planet carrier member; wherein the firstplanetary member of the second planetary gearset is a ring gear member;wherein the second planetary member of the second planetary gearset is asun gear member; wherein the third planetary member of the secondplanetary gearset is a planet carrier member; wherein the firstplanetary member of the third planetary gearset is a ring gear member;wherein the second planetary member of the third planetary gearset is asun gear member; and wherein the third planetary member of the thirdplanetary gearset is a planet carrier member.
 10. A transmissioncomprising: an output member; a first planetary gearset and a secondplanetary each having a respective first planetary member, a respectivesecond planetary member, and a respective third planetary member; saidplanetary members of the first planetary gearset being coaxiallydisposed on, and selectively rotatable about, a first axis; saidplanetary members of the second planetary gearset being coaxiallydisposed on, and selectively rotatable about, a second axis; said outputmember being selectively rotatable about a third axis; at least one axistransfer mechanism operatively interconnecting one of the planetarymembers of the first planetary gearset, one of the members of the secondplanetary gearset, and the output member; wherein said at least one axistransfer mechanism is configured such that torque is transmissible fromthe first planetary gearset and from the second planetary gearset to theoutput member through said at least one axis transfer mechanism; whereinsaid at least one axis transfer mechanism includes a first axis transfermechanism and a second axis transfer mechanism; wherein the first axistransfer mechanism includes a first axis transfer gear member, a secondaxis transfer gear member meshingly engaged with the first axis transfergear member, and a third axis transfer gear member meshingly engagedwith the second axis transfer gear member; wherein the second axistransfer mechanism includes a fourth axis transfer gear memberoperatively connected to the first axis transfer gear member for unitaryrotation therewith, a fifth axis transfer gear member meshingly engagedwith the fourth axis transfer gear member, a sixth axis transfer gearmember operatively connected to the fifth axis transfer gear member forunitary rotation therewith, and a seventh axis transfer gear membermeshingly engaged with the sixth axis transfer gear member andoperatively connected to the output member for unitary rotationtherewith.
 11. The transmission of claim 10, further comprising an inputmember; a stationary member; a first motor/generator having a firstrotor; a second motor/generator having a second rotor; wherein the firstmember of the first planetary gearset is operatively connected to thefirst axis transfer gear member for unitary rotation therewith; whereinthe second member of the first planetary gearset is operativelyconnected to the first rotor for unitary rotation therewith; wherein thethird member of the first planetary gearset is operatively connected tothe input member for unitary rotation therewith; wherein the firstmember of the second planetary gearset is operatively connected to thestationary member such that the first member of the second planetarygearset is not rotatable with respect to the stationary member; whereinthe second member of the second planetary gearset is operativelyconnected to the second rotor for unitary rotation therewith; andwherein the third member of the second planetary gearset is operativelyconnected to the third axis transfer gear member for unitary rotationtherewith.
 12. The transmission of claim 11, wherein the first planetarymember of the first planetary gearset is a ring gear member; wherein thesecond planetary member of the first planetary gearset is a sun gearmember; wherein the third planetary member of the first planetarygearset is a planet carrier member; wherein the first planetary memberof the second planetary gearset is a ring gear member; wherein thesecond planetary member of the second planetary gearset is a sun gearmember; and wherein the third planetary member of the second planetarygearset is a planet carrier member.